Classic Shell™ is free software that improves your productivity, enhances the usability of Windows and empowers you to use the computer the way you like it. The main features are:
-Highly customizable start menu with multiple styles and skins
-Quick access to recent, frequently-used, or pinned programs
-Find programs, settings, files and documents
-Start button for Windows 7, Windows 8, Windows 8.1 and Windows 10
-Toolbar and status bar for Windows Explorer
-Caption and status bar for Internet Explorer

I did install it on my Win8 machine, but by the time Win10 came out, I realized I barely use the start menu anymore, and when I do, it's faster to just type than to go through the hierarchy. So I don't think I've installed it on any Win10 systems.

I have ClassicShell on all my Win 7 and Win 10 machines. I like that it allows me to have identical keystrokes for accessing software on different machines. I used to spend time tweaking my Start menus on various Thinkpads running Win 98SE and XP so that commonly used software or folders could be opened up in 3 single key strokes: Start Button -> Folder Letter -> Program. With ClassicShell, many of the shortcuts I got used to under Win98 and XP can still be used today in Win 10. And whenever I pull out an old machine, almost all my software is still at my fingertips, right where I expect it.

Apparently, Windows 10 major updates were causing too many feature-breaking changes for the awesome lead developer Ivo Beltchev.
There is a Github repository for a forked replacement called "Open-Shell", but it is not clear to me how much development is occurring on it: https://github.com/Open-Shell/Open-Shell-Menu

I have been concerned with each major Windows 10 update whether ClassicShell would continue to work. I'm running v4.3.1 that was released way back in August 2017, and it is the first thing I check for compatibility whenever I apply the next major Windows 10 update.

I used to spend time tweaking my Start menus on various Thinkpads running Win 98SE and XP so that commonly used software or folders could be opened up in 3 single key strokes: Start Button -> Folder Letter -> Program. With ClassicShell, many of the shortcuts I got used to under Win98 and XP can still be used today in Win 10. And whenever I pull out an old machine, almost all my software is still at my fingertips, right where I expect it.

That's an interesting approach and I understand why Classic Shell is a godsend in such a scenario. I went a different path - I put icons for commonly used software on my desktop / quick launch and assign keyboard shortcuts. That's probably why the Start menu lost a lot of its importance to me.

Another nifty program is Clover which adds Chrome-style tabs to the top of Windows Explorer windows. This is apparently a feature coming to 10 (or it came already, I haven't touched 10 in a long time) so I looked into the existing softwares for myself. It doesn't work right with Lenovo Auto Scroll but it's otherwise really useful to me.

I've been using it but I'm thinking of going back to the old start menu. I find it kind of a PITA because of its inadequate support for the Settings control panel.

And don't even get me started on W10 using both the "Control Panel" and "Settings"

Either one or the other...not both. I actually do kinda prefer Settings more intuitive way of getting to the things I need and better support for Bluetooth.

Thinkpad4by3's Law of the Universe.

The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

I am a user too on Wins 7 and 10.
Interestingly I am a fan of keyboard shortcuts too but by using entries in the Classic start menu that link to opening programs (apps) folders and even windows/file explorer at a specific folder open position, all with just one keystroke its quick and easy.
The only problem is remembering the correct shortcut ! Although as I have been using the same basic shortcuts since Win 2000 they are used more by instinct than memory. Some have fallen by the wayside, for example 'a' no longer opens the floppy drive.